piechart: A flexible piechart.

Description

While similar to graphics::pie(), this function is much more flexible as it allows providing different parameters for each slice of the pie. Furthermore, it allows adding the plot to the current device, making it possible to create compound piecharts.

Usage

piechart(
  x,
  labels = names(x),
  radius = 1,
  doughnut = 0,
  origin = c(0, 0),
  edges = 200,
  slice.off = 0,
  init.angle = 0,
  last.angle = 360,
  tick.len = 0.1,
  text.args = list(),
  segments.args = list(),
  skip.plot.slices = FALSE,
  add = FALSE,
  rescale = TRUE,
  ...
)

Value

A list with the following elements:

slices: A list of length length(x) with the coordinates of each slice.
textcoords: A numeric matrix of size length(x)*2 with coordinates where the labels can be put at.
alpha0: A numeric vector of size length(x) with the starting degree in radians of the slice.
alpha1: A numeric vector of size length(x) with the ending degree in radians of the slice.

Arguments

x: Numeric vector. Values that specify the area of the slices.
labels: Character vector of length length(x). Passed to graphics::text().
radius: Numeric vector. Radious of each slice (can be a scalar).
doughnut: Numeric scalar. Radious of each inner circle (doughnut) (can be a scalar).
origin: Numeric vector of length 2. Coordinates of the origin.
edges: Numeric scalar. Smoothness of the slices curve (can be a vector).
slice.off: Numeric vector. When !=0, specifies how much to move the slice away from the origin. When scalar is recycled.
init.angle: Numeric scalar. Angle from where to start drawing in degrees.
last.angle: Numeric scalar. Angle where to finish drawing in degrees.
tick.len: Numeric scalar. Size of the tick marks as proportion of the radius.
text.args: List. Further arguments passed to graphics::text().
segments.args: List. Further arguments passed to graphics::segments() when drawing the tickmarks.
skip.plot.slices: Logical scalar. When FALSE, slices are not drawn. This can be useful if, for example, the user only wants to draw the labels.
add: Logical scalar. When TRUE it is added to the current device.
rescale: Logical scalar. When TRUE (default), the y-coordinates of the polygons (slices), text and tickmarks will be rescaled such that the aspectt ratio is preserved, i.e. looks like a circle.
...: Further arguments passed to graphics::polygon() (see details).

Details

The function is a wrapper of graphics::polygon(), so all parameters such as color, density, border, etc. are passed directly by mapply() so that are specified one per slice. The coordinates of the slices are computed internally.

Examples

Run this code


# Example 1 -----------------------------------------------------------------
# A set of 3 nested rings rings starting at 315 deg. and ending at 270 deg.

# Values to plot
vals <- c(1,2,3,10)

# Outer (includes labels)
piechart(vals, col=grDevices::blues9[5:8], border=NA, doughnut = .5,
    radius=.75, labels=vals, init.angle = 315, last.angle = 270)

# Middle
piechart(vals, col=grDevices::blues9[3:6], border=NA, doughnut = .3,
    radius=.5, add=TRUE, init.angle = 315, last.angle = 270)

# Inner
piechart(vals, col=grDevices::blues9[1:4], border="gray", doughnut = .1,
    radius=.3, add=TRUE, init.angle = 315, last.angle = 270)

# Example 2 -----------------------------------------------------------------
# Passing values to polygon and playing with the radius and slice.off

piechart(1:10, density=(1:10)^2/2, slice.off = (1:10)/30, doughnut = .5,
  radius = sqrt(10:1),
  # Here we are setting random labels...
  labels=sapply(1:10, function(x) paste(sample(letters, x, TRUE), collapse=""))
  )